Intensive study in recent years of the role of Clostridium perfrngens enterotoxin in digestive disease has elucidated important and revealing information concerning the structure and function of the gut and individual cells. Initial studies have revealed gross observable changes induced by the enterotoxin in transport of fluid and electrolytes, and morphological damage to the intestine. Most recently we have begun to characterize in detail cellular biochemical changes, membrane-toxin interactions, and ultrastructural alterations caused by the action of this enterotoxin that is responsible for one of the most common types of food poisoning in the United States today. The proposed research will 1) further characterize the structural and functional changes induced in sensitive cell membranes at the biochemical and ultrastructural levels. This includes, hopefully, the isolation and identification of an enterotoxin "receptor" from cell membranes. It also will 2) provide new tools to study and trace the enterotoxin through its production in a radiolabeled form. This will involve further characterization and utilization of an in vitro protein synthesis system we have already developed. Of broader scope, this research will 3) continue to contribute to the understanding of intestinal epithelial cell membrane structure, configuration and function through analysis of interactions and alterations resulting from the biological activity of the enterotoxin.